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- Trophic-mediated pelagic habitat structuring and partitioning by sympatric elasmobranchsPublication . Afonso, André S.; Macena, Bruno C.L.; Mourato, Bruno; Bezerra, Natalia P.A.; Mendonça, Sibele; Queiroz, Joyce D.G.R. de; Hazin, Fábio H.V.Pelagic elasmobranchs are key elements of oceanic ecosystems and must be preserved if marine trophic networks are to be kept in balance. Yet, they face intense fishing pressure that has been threatening their populations worldwide. Ensuring proper conservation management of these taxa depends on a better understanding of the strategies they use to explore the pelagic realm and their contributions to trophic web structuring across the ocean column. This study aimed at examining relationships between vertical habitat use and trophic attributes among six sympatric pelagic elasmobranchs using satellite transmitting tags in the western equatorial South Atlantic Ocean. The vertical movements of 35 elasmobranch individuals were tracked during an overall total of 1911 days. Clear relationships between species’ feeding habits, maximum diving depths, and proportion of time spent either in epipelagic or in surface waters were evidenced by Bayesian generalized linear mixed models and multivariate analysis. Filter-feeders made most use of deep waters from the mesopelagic and bathypelagic and shifted their diving depths in phase with diel vertical migrations of the deep scattering layer, i.e., shallower during the night and deeper during the day. Specialists exhibited distinct diving patterns in epipelagic and mesopelagic waters across the diel period which are potentially indicative of habitat partitioning, whereas generalists were more surface-oriented but also explored deeper waters compared to specialists. The trophic level also seemed to influence elasmobranch maximum diving depths, which tended to become shallower as species’ trophic level increased. These results corroborate previous evidence of widespread vertical habitat partitioning among sympatric pelagic predators and depict a trophicmediated structuring of the pelagic environment where top-down control may be exerted at different depths by distinct species. Further research is yet required to understand the role of elasmobranch vertical movements in structuring pelagic habitats as well as to guide ecosystem-based fisheries management aimed at reducing species susceptibility to fishing gear and at preserving the structure and functionality of marine trophic networks.
- The effect of light attractor color in pelagic longline fisheriesPublication . Afonso, André S.; Mourato, Bruno; Hazin, Humberto; Hazin, Fábio H.V.Improving the selectivity of the fishing gear is one of the most promising methods to mitigate deleterious impacts of longline fisheries upon bycatch species. Light lures have recently become widespread in epipelagic longline fisheries since they increase the catch rates of valuable target species such as swordfish and tunas. Yet, little is known about their effect upon the incidence of bycatch. Here, we compared the catchability of target and bycatch species in a pelagic longline fishery targeting swordfish and tunas equipped with light attractors with three different colors to ascertain if any of the light attractor colors would enhance the selectivity of the fishing gear. A total of 3488 individuals were caught across 57 fishing sets. The proportion of target species to bycatch species was high (58–65 %) in each color treatment. Overall, green attractors (peak wavelength at 525 nm) exhibited the highest catch rates of target species, but they were also responsible for the highest incidence of bycatch, rendering 73 % and 82 % of the blue shark and sea turtle catch, respectively. Blue (peak wavelength at 465 nm) and white attractors caught significantly less individuals of both target and bycatch species. Further, significant interactions between light attractor color and the intensity of lunar illumination were observed for most species analyzed. Differences in the catchability of bycatch such as blue sharks and white marlins across attractor color treatments were more conspicuous at high lunar illumination levels (i.e. full moon periods), when white attractors rendered the lowest catch of these taxa. In contrast, the catchability of target species such as swordfish, yellowfin tuna and albacore showed greater differences between treatments at low illumination levels (i.e. new moon periods). The observed differences in the performance of the three light attractor colors across the lunar cycle might provide an opportunity to mitigate bycatch incidence in longline fisheries. Yet, further research is required to fully understand the combined effects of light lures and lunar illumination on the behavioral responses of pelagic species.
- Public support for conservation may decay with increasing residence time in suboptimal marine protected areasPublication . Afonso, André S.; Fidelis, Leonardo L.; Roque, Pedro L.; Galindo, Renato; Dionisio, Wanderson; Veras, Leonardo B.; Hazin, Fábio H.V.Marine Protected Areas (MPAs) are potentially effective conservation and management instruments yet they often produce socioeconomic conflicts which may challenge their success. Knowledge and perceptions about environmental subjects among MPA residents were examined to identify possible effects of conservation policies upon local communities. Sharks were used as a proxy for wildlife given their local relevance and socioenvironmental context. Self-administered questionnaires were used to collect data from 134 randomly-selected residents of Fernando de Noronha (FEN), Brazil. Affinity towards nature tended to decrease among people>44 years old, whereas>10 years residents were more associated with negative feelings about sharks. Homogeneity in knowledge was noticed but perceptions decreased conspicuously across residence time-classes. Only 33% of respondents reported unarguable MPA benefits to local welfare, while several problems pertaining to infrastructure, management and resources were mentioned. These results are worrisome because they might translate into growing frustration along with residence time, which could potentially jeopardize the success of conservation policies. Wildlife conservation and at least partial improvements to welfare being positively signalized by a relevant proportion of respondents suggest an encouraging potential for relationship improvement between MPAs and stakeholders. Nonetheless, the long-term sustainability of inhabited MPAs could depend on properly integrating human users and ensuring their support and compliance, which must be considered while designing management strategies. Given the prestige of FEN in the South Atlantic and worldwide, it is important that this MPA delivers successful, sustainable outcomes that can be representative of efficient conservation trajectories to be replicated elsewhere.
- Ecological features of a rocky intertidal community exposed to sewage effluentPublication . Conde, Anxo; Pacheco, Joana; Marques, Sónia Cotrim; Afonso, André S.; Leandro, Sérgio; Maranhão, PauloSewage is among the largest components of coastal pollution, showing a variable scale and size when causing an impact. In this study, temporal and spatial sewage-related gradients were identified using univariate and multivariate methods. Phosphates and nitrogen-based nutrients, except nitrate, were associated to sewage. Abundance and species richness decrease with distance from the sewage outfall while evenness increased. Filterfeeder bivalves and grazer crustaceans showed preference for the sewage discharge site. Gastropods were more abundant at an intermediate distance, likely reflecting primary production enhancement by sewage. Beta diversity was lower at the location and time with highest sewage loadings. The turnover component of beta diversity expressed as an absolute or proportional value was also useful to detect temporal and spatial sewagerelated gradients. Highly energetic hydrodynamics contributes to ameliorate sewage impacts, yet not enough to veil the effect of pollution in this study.
- Reply to: Shark mortality cannot be assessed by fishery overlap alonePublication . Queiroz, Nuno; Humphries, Nicholas E.; Couto, Ana; Afonso, André S.; Sims, David W.; Afonso, Pedro; Bezerra, Natalia P.A.; Fontes, Jorge; Hazin, Fábio H.V.; Macena, Bruno C.L.; Travassos, Paulo; Vandeperre, Frederic; Vedor, Marisa; Costa, Ivo da; Sequeira, Ana M.M.; Santos, António M.; Mucientes, Gonzalo; Abascal, Francisco J.; Abercrombie, Debra L.; Anders, Darrell; Araujo, Gonzalo
- Abundance dynamics of a new, endemic batoid from Brazil: The Lutz’s stingray, Hypanus berthalutzaePublication . Branco-Nunes, Ilka; Niella, Yuri; Hazin, Fábio Hissa Vieira; Creio, Emmanuelly; Oliveira, Paulo Guilherme Vasconcelos de; Afonso, André SucenaThe Lutz’s stingray, Hypanus berthalutzae, is a recently identified, endemic dasyatid species which occurs in shallow habitats exclusively along most of the Brazilian coast. It is frequently caught as bycatch in different fisheries throughout the range of its distribution, but information on population trends and the impacts of fishing is still scarce. Therefore, this study aimed to describe the structure and dynamics in H. berthalutzae relative abundance off Recife, Northeast Brazil, in order to provide baseline data for species management. H. berthalutzae were caught and sampled in a fisheries-independent, standardized longline and drumline survey which used > 500,000 hooks during ∼11 years. H. berthalutzae catch composition (N = 86) was characterized by a striking predominance of females, with a female:male ratio of 16:1. Most of these individuals measured were considered to be mature. H. berthalutzae catch rates were largely reduced after hooks previously operating directly on the seafloor were suspended in the middle of the water column. Such an effect was included in a zero-inflated generalized additive model developed to assess spatiotemporal and environmental modulators of H. berthalutzae abundance, for which both month and lunar phase proved to be statistically significant predictors. A higher abundance of H. berthalutzae was observed in the rainy season, from March to July (χ2= 19.22; p < 0.001), as well as during full moon periods (Z = 2.38; p = 0.017). The effects of other candidate predictors such as sampling site or year were either nonexistent or superimposed by other more deterministic factors. The results achieved in this fully standardized survey depict the dynamics in adult H. berthalutzae which might be expected to occur in coastal habitats off northeastern Brazil, thus providing a solid contribution to improve the management of local artisanal fisheries towards the recovery and sustainability of H. berthalutzae populations across their range.
- Global spatial risk assessment of sharks under the footprint of fisheriesPublication . Queiroz, Nuno; Afonso, André S.; Humphries, Nicholas E.; Sims, David W.Effective ocean management and conservation of highly migratory species depends on resolving overlap between animal movements and distributions and fishing effort. Yet, this information is lacking at a global scale. Here we show, using a big-data approach combining satellite-tracked movements of pelagic sharks and global fishing fleets, that 24% of the mean monthly space used by sharks falls under the footprint of pelagic longline fisheries. Space use hotspots of commercially valuable sharks and of internationally protected species had the highest overlap with longlines (up to 76% and 64%, respectively) and were also associated with significant increases in fishing effort. We conclude that pelagic sharks have limited spatial refuge from current levels of high-seas fishing effort. Results demonstrate an urgent need for conservation and management measures at high-seas shark hotspots and highlight the potential of simultaneous satellite surveillance of megafauna and fishers as a tool for near-real time, dynamic management.
- Reply to: Caution over the use of ecological big data for conservationPublication . Queiroz, Nuno; Humphries, Nicolas E.; Couto, Ana; Afonso, André S.; Sims, David W.; Afonso, Pedro; Bezerra, Natalia P. A.; Fontes, Jorge; Hazin, Fábio H.V.; Macena, Bruno C.L.; Travassos, Paulo; Vandeperre, Frederic; Vedor, Marisa; Costa, Iva do; Sequeira, Ana M.M.; Mucientes, Gonzalo; Santos, António M.; Abascal, Francisco J.; Abercrombie, Debra L.; Abrantes, Katya; Acuña-Marrero, David; Ferreira, Luciana C.; Ladino, Felipe; Lana, Fernanda O.; Quintero, Lina Maria; Duarte, Carlos M.
- Population genetics reveals global and regional history of the apex predator Galeocerdo cuvier (carcharhiniformes) with comments on mitigating shark attacks in north-eastern BrazilPublication . Andrade, Flávia R.S.; Afonso, André S.; Hazin, Fábio H.V.; Mendonça, Fernando F.; Torres, Rodrigo A.The knowledge of the population structure of a given species is of great importance for its conservation and for the management of its fishing exploitation, especially for sharks. The tiger shark (Galeocerdo cuvier Péron&Lesueur, 1822) is an apex predator species that is currently listed as “Near Threatened” on the International Union for the Conservation of Nature's (IUCN) Red List of Threatened Species. In this study, the tiger shark's genetic structure in the Metropolitan Region of Recife (MRR) and oceanic archipelago of Fernando de Noronha (FN) was investigated based on one mitochondrial and two nuclear DNA markers. In addition, sequenced data from other geographic sites were added into the mitochondrial analysis. The data showed moderate-to-high genetic diversity, and it is consistent with good resilience of G. cuvier in ecological terms. The structuring tests reinforced a global distinction of the species in two lineages, one being from the Indo-Pacific and the other from the North Atlantic. Also, this analysis showed the close relationship between tiger sharks from Indo-Pacific and South-eastern coast of Brazil. The Bayesian and AMOVA tests indicated that tiger sharks from FN and MRR are genetically similar, forming a cohesive population. These analyses support live specimen translocations from beaches (where the attacks occur) to distant marine areas given we detected a historical cohesive population occurring between those beaches from MRR and FN Islands where the sharks migrate. This research is the first that has validated individual translocations as a green strategy in South-western Atlantic.
- Does lack of knowledge lead to misperceptions? Disentangling the factors modulating public knowledge about and perceptions towards sharksPublication . Afonso, André S.; Roque, Pedro; Fidelis, Leonardo; Veras, Leonardo; Conde, Anxo; Maranhão, Paulo; Leandro, Sérgio; Hazin, Fábio H.V.Identifying sources of variability in public perceptions and attitudes toward sharks can assist managers and conservationists with developing effective strategies to raise awareness and support for the conservation of threatened shark species. This study examined the effect of several demographic, economic and socioenvironmental factors on the quality of knowledge about and perceptions toward sharks in two contrasting scenarios from northeastern Brazil: a shark hazardous coastal region and a marine protected insular area. Ordered logistic regression models were built using Likert data collected with a self-administered questionnaire survey (N = 1094). A clear relationship between education, knowledge and perceptions was found, with low education level and knowledge of sharks resulting in more negative perceptions toward these species. Prejudice toward sharks stemmed as a potentially limiting factor because the positive effects of other variables such as affinity for nature and specific knowledge about sharks were superseded by the effects of negative prejudice. Other practical factors such as age, economic level, and gender, also influenced respondent’s knowledge and perceptions and could provide a guidance for optimizing socioenvironmental gains relative to public engagement efforts. Results also suggested that populations inhabiting regions with high shark bite incidence likely require distinct outreach methods because some factors underlying knowledge and perception dynamics exhibited structural differences in their effects when compared to the trends observed in a marine protected area. Altogether, public perceptions and attitudes toward sharks could be feasibly enhanced with educational development and nature experiencing strategies. Moreover, disseminating shark-specific knowledge across the society might catalyze support for the conservation of these species in a cost-effective way. This study provides a Frontiers in potentially useful socioenvironmental framework to deal with the human dimensions of shark management and to strengthen conservation policies aimed at promoting societal compliance with pro-environmental values, which is crucial to endow shark populations with effective protection from anthropogenic threats.